Why was there a decrease in breast cancer occurrence after the Women’s Health Initiative (WHI) caused many women to stop taking hormones? Dr. Heward: For why we see more breast cancer in women on hormones in clinical studies, the truth is that you would expect, even out there in free living people in clinical environments, if there are lots of women in a community who are on hormones and some of them get breast cancer, those women who get breast cancer are going to have their tumor show up faster if they are on hormones, and the hormones are causing those cancers to grow faster. So, if we now stop giving the women in the community hormones then the rate of cancer incidents for a period of time is going to be slower than it had been in the population overall when some of the population was on hormones. So, that’s the period that we're going in, and what I would predict, if the hypothesis that I am promulgating here is correct, is that we’ll see a reversal of that phenomenon as the time frame, if in fact the number of women who are avoiding hormones remains the same and the time frame for that avoidance is long enough.

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